With AF I would say that it almost fully dependent on the mood of the people you deal with and if there is a rational supervisor nearby. Two examples (both with hand luggage only):
Incoming flight was early and I had an hour and a half to catch the earlier flight on discounted business ticket, showed up at gate, quickly explained the situation, agent punched keys for a minute and handed me boarding pass with barely a word said.
Another time on a FULL WHACK Biz ticket, incoming flight ontime, but earlier CDG-JFK flight delayed by an hour. Show up at gate and explain situation and told, "Impossible biz is full". I ask how could they possibly know if everyone had boarded as they had not started boarding yet. I say that I will wait (afterall I had 5 hours until my flight). 45 minutes later and half an hour before the flight am approached by an AF person asking why I am not boarding. I explain the situation and am told again, "Impossible". I say that I'll wait, the guy is uncomfortable with that.
15 minutes before flight time a supervisor comes over and checks with the staff as to how things are going. She asks in France why I have not boarded. before the guy can answer, I jump in and explain my situation. She glares at the guy and mutters, "LAZY ......." at him (In French). He nervously fumbles with the computer and hands me a boarding pass. I discovered that there were THIRTY FIVE empty Biz seats on the flight, and asked the Purser...they were fully catered for all seats (before anyone jumps to that conclusion). I should also note that I was flying the flight as a AF Platinum and on a full J ticket with carry on only baggage if i did not mention it before!